Brown — Mechanical Stress and Magnetisation of Iron. 103 



The top of tlie wooden giiide-frame F has a scale marked on it which is 

 divided into spaces of 10 degrees, from to 180 round eacli half. 



The wire 7i Founder test could be put in circuit — through the plug key K, 

 — with a sensitive moving coil ballistic min-or galvanometer BG of the 

 Ayrton and Mather type, with a coil of resistance 325 ohms. 



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An earth-inductor E could also be put in circuit with the galvanometer 

 and wire, by opening the key K, and closing A' ; this was for the purpose of 

 testing or checking the constant of the galvanometer during the progress of 

 the work. At the beginning and end of every set of observations on the 



T 2 



